Carriage feeding escapement mechanism



Aug. 18, 1953 J. P. BARKDOLL 2,649,179

' CARRIAGE FEEDING ESCAPEMENT MECHANISM Filed April 29, 1950 I FIG. I

JOSEPH P. BARKDOLL INVENTOR ATTORNEY Patented Aug. 18, 1953 STATES PATENT QFFICE CARRIAGE FEEDING ES CAPEMENT MECHANISM Application April 29, 1950, Serial No. 158,985 6 Claims. (61.197-88) The invention relates to improvements in carriage feeding escapement mechanism, the improved mechanism. being particularly adapted for use as an escapement for reciprocable platen or other carriages of typewriting and calculating machines.

The principal purposes of the invention are to provide a carriage escape-ment wherein feeding of the carriage is controlled by a holding dog and by a stepping dog which is driven against the holding dog to insure feeding of the carriage through uniform steps; to provide a full drop escapement which will feed a carriage very rapidly and silently through uniform steps and will permit silent return of the carriage without the necessity of releasing the carriage from the es capement; and to provide an escapement which consists of a very few parts all of which are of simple and inexpensive construction and so constructed and arranged that no relative adjustments of the escapement dogs are at any time required to insure feeding of the carriage through uniform steps and to prevent derangement or jamming of the escapement.

Other purposes and advantages of the invention will appear from the following description in detail of the preferred. embodiment of the invention which is illustrated by way of example in the accompanying drawing.

In the drawing:

Figure 1 is a fragmentary vertical sectional view on the line ll of Figure 2 showing the vention embodied in a known typewriting machine with the parts of the improved escapement in their normal carriage holding relation;

Figure 2 is a fragmentary top plan view of the machine with certain parts broken away to more clearly show the improved escapement, the escapement parts being shown in their normal carriage holding relation;

Figure 3 is a fragmentary vertical sectional view on the line 38 of Figiu'e 2 showing the escapement tripped and holding the carriage at the end of a feed step or movement of the carriage;

Figure 4 is a fragmentary bottom plan View of the escapement with the parts positioned as in Figures 1 and 2;

Figure 5 is a detail vertical sectional View on the line 55 of Figure 2; and

Figure 6 is a view similar to Figure 4 showing the escapement in its tripped condition illustrated in Figure 3.

Only so much of the known typewriting machine is shown and will be described as is neces- 2 sary for a full understanding of the invention by those skilled in the art.

The horizontally reciprocable platen carriage l0 carries a platen H and travels transversely of the machine on suitable ball bearings l2 which are confined in raceways formed on the carriage and on a carriage supporting and guiding part l3 of the stationary framework of the machine. As is common in the art, the reciprocably supported carriage is urged from right to left by a spring, not shown, and is fed step by step from right to left horizontally across the machine for letter spacing and is returnable from left to right. In Figure 2 of the drawing the arrows associatcd with the section lines l-l and 33 point toward the left hand side of the machine. The step by step or letter spacefeeding of the carriage is effected through the medium of the improved escapement mechanism, certain known parts of which now will be described.

Part #3 of the machine framework forms a carriage bed to which is fixed a bracket l 4 which likewise forms part of the machine framework. An upstanding feed shaft #5 is rotatively journaled at its upper and lower ends by suitable bearings carried by bracket i4 and has fixed thereto a pinion l6 and a carriage feeding escapement ratchet wheel or ratchet toothed circular carriage feeding rack l1. Pinion It meshes with a horizontal rack I8 which extends longitudinally of the carriage and behind the feed pinion and is fixed to the carriage. It will be obvious to those skilled in the art that the rack I i may be a straight rack movable endwise with the carriage and substituted for the parts l5, 16, I1, and It, as is common in the art.

The improvements in the escapement mechanism now will be described as they are embodied in the preferred construction shown in the drawing.

Bracket 14 carries two axially aligned horizontal pivots [9 on which a dog rocker 2G is pivoted to rock relatively to wheel l! about a horizontal axis which is parallel to the plane of said wheel and preferably lies approximately in the plane of the wheel, said clog rocker in the machine shown being located behind the feed shaft. Preferably, the dog rocker is formed of sheet metal and has two side arms which are journaled on pivots l9 and are rigidly connected by a flat main body part of the dog rocker. This dog rocker is tripped or rocked on its pivot from the normal position thereof shown in Figures 1, 2 and 4 into the tripped position shown in Figures 3 and 6 by known mechanism, not shown,

and is restored by a contractile return spring 2| connected to the bracket l4 and the dog rocker.

The spring 2! normally yieldingly holds the dog rocker with a stop lug 22 on the rocker abutting a downwardly facing stop edge portion or abutment 23 on bracket I4. In the normal posltion of the rocker, preferably, the flat body part thereof lies approximately in the plane of the wheel IT. The forward edge of the flat body part of the rocker is spaced from the toothed periphery of the wheel to permit escapement tripping rocking movement of the rocker.

A holding dog 24 and a stepping dog 25 are pivoted on shoulder portions of conventional shouldered pivot bolts 26 and 21, respectively, which have their reduced threaded shank portions screwed through threaded holes in the flat main part of the dog rocker, the bolt 26 being screwed up through said dog rocker part and the bolt 21 being screwed down therethrough, the shoulder portions of said bolts abutting respectively the lower and upper faces of said dog rocker part. Nuts 28 and :29 are screwed on bolts 25 and 21 respectively.

Each of the dogs projects from its pivot to points beyond both the front and rear edges of the main fiat part of the dog rocker and is held against canting by the head of its pivot bolt and the adjacent face of said dog rocker, each said dog being formed of flat sheet steel corresponding in thickness to the length of the pivot shoulder of its pivot bolt and having its nose at its forward end. The holding and stepping dogs are thus supported to swing in parallel planes about parallel pivots. nected at their rear ends to opposite ends of a contractile return spring 33 which normally swings the dogs around their respective pivots into their normal positions in which the spring presses the dogs against a sound deadening stop device 3|--32 which now will be described.

The stop device 3 l32 comprises a sheet metal member 3| which is clamped at one end thereof to the top of the flat main body part of the dog rocker by nut 28 with the shank of pivot bolt 26 of the stepping dog engaged in a hole in said end of member 3 I. The other end of member 3! is of inverted channel form and is lined or padded with a thin sheet 32 of rubber or other suitable sound deadening material bent to inverted channel form therein. The padded stop device 3 l--32 thus has two padded pendent stop legs 3| and 31 These legs straddle a narrow portion of the fiat main body part of the dog rocker one edge of which narrow portion constitutes one edge of a hole 33 in said rocker part through which the padded leg 3l depends.

Spring 30 normally holds the nose carrying arm of the holding dog 24 rocked toward the left hand side of the machine against the padded face of leg 3l During return of the carriage, said arm of dog 24 is rockable toward the padded face of leg 3| by the teeth of the wheel [1 far enough to permit the wheel teeth to pass the nose of said dog without said dog striking the padded leg 3 l In the event of very violent return of the carriage said dog arm may lightly collide with the padded face of leg 3| to limit overthrow.

The stepping dog 25 has a stop lug 34 extending therefrom adjacent the pivot 21 of the dog toward the dog 24 and behind the padded stop leg 3 l said lug being normally held rocked forward by spring 30 against the rear edge of the padding of leg 3| and, preferably, the adjacent The dogs are conwith the padding at the face of leg 3 l abutting the adjacent edge of hole 33 and with a protruding forward edge of the padding of said leg abutting the forward end of said hole, as shown.

The thickness of the ratchet wheel ll preferably is such, as best apparent from Figure 3, that the nose of neither dog will fully disengage from the wheel until the nose of the other dog engagesthe wheel or is in position to be engaged, i. e. is Within the planes of the upper and lower faces of the wheel, thus preventing accidental skipping of the carriage through more than one letter space in the event of very slow rocking of the dog rocker. To the above end, and to permit forming of the rocker and wheel of thin stock, the nose of the stepping dog 25 may be bent down part way toward the plane of movement of the nose of the holding dog 24, as best shown in Figure 3. Preferably the wheel tooth holding edge of the stepping dog 25 is beveled from top to bottom, as indicated at 25*, and as is common in the art, to provide a cam surface for action of the held tooth thereon to repulse the dog rocker and assist spring 2| to quickly return the dog rocker to normal position.

To positively arrest stepping movement of the stepping dog 25 in an invariable relation to the holding dog 24 for accurate and uniform step feeds of the carriage, a metal stop pin 35 is fixed to dog 25 near the nose of dog 25 and depends from said dog in position to move against a stop projection 36 formed integrally with the holding dog 24 near the nose of said holding dog. The dogs could be formed with other suitable rigid mutually abuttive stops than the specific stops 35 and 36. Stops 35 and 36 abut opposite stop leg 3| and near the noses of the dogs and transmit the shock of carriage arrest substantially directly toward said stop leg and without subjecting the dog pivots to objectionable strain. In the construction shown, the wheel tooth holding edges of the dogs are in register or practically so when stops 35 and 35 are engaged. Where edge 25 is beveled, its upper or top side may protrude, as shown in Figure 6, while parts 35 and 36 are engaged Without appreciably altering the functioning of the escapement as a full drop escapement.

When the dog rocker is rocked from its normal position of Figures 1, 2, and 4 into its tripped position of Figures 3 and 6 the wheel ll turns one tooth space under the force of the platen carriage advancing spring (not shown), thus feeding the carriage one letter space. When the rocker is so tripped, the holding dog 24 releases the held tooth of the wheel l'l, and just before this release is completed and before the rocker reaches its fully tripped position, the rocker carries the stepping dog far enough to interpose its nose in the path of the next advancing wheel tooth, which tooth engages the stepping dog and rocks it on its pivot until stops 35 and 33 engage. On the return stroke of the dog rocker, the nose of the holding dog engages the wheel tooth then being held by the stepping dog before the stepping dog fully disengages said tooth and the carriage will remain held by the holding dog as the dog rocker completes its return movement and until the rocker is again tripped. Spring 30 restores the stepping dog as soon as that dog is released from wheel I7.

During return of the carriage the Wheel teeth rock the holding dog 24 on its pivot against the pull of spring 30 far enough to permit the teeth to pass said dog. The padded stop 3I-32 quietly limits pivotal restoration of dogs 24 and 25 by the single spring 30. The padded stop also cushions and quietly absorbs the shock of arrest of the carriage at the end of each feed movement since this shock is transmitted through the then mutually abutted dogs to the padded leg 3| a of the padded stop, as will be apparent from Figure 6.

Should the padding 32 of the stop device 3 l-32 alter with age, or with changes in atmospheric conditions, the uniformity of the carriage feed steps will not alter. No adjustable stops are required. for either of the escapement dogs to insure proper feeding of the carriage.

It will be noted that the dogs abut at 35-36 near their noses and opposite the stop leg 31* so that the dog pivots are not subjected to bjectional strain in bringing the carriage to rest when the escapement is tripped, the line of shock being substantially directly to stop leg 3 l The several parts of the escapement are exceedingly few in number, cheap to manufacture, easy to assemble and require no great precision in manufacture or assembly.

I claim:

1. A carriage feeding escapement mechanism comprising a carriage feeding rack mounted and urged for stepping movement in one direction, holding and stepping dogs having noses engageable by the teeth of said rack to control stepping movements of the rack, a dog rocker for interposing the noses of said dogs alternately in position for toothed engagement of the rack therewith, means pivotally mounting the stepping dog on the rocker for movement about an axis to step with the rack from a normal position of said dog to a stepped position when the rack makes toothed engagement with the nose of said dog, means mounting the holding dog on the rocker for collision therewith of the stepping dog as the latter reaches its stepped position to thereby arrest stepping movements of the stepping dog and rack, said mounting means for the holding dog mounting said dog for pivotal movement from a normal position of said dog by reverse movement of the feed rack, said dogs having means adjacent their noses collisive to arrest stepping movements of the stepping dog and located closer to the noses of the dogs than is the pivotal axis of the stepping dog, means to automatically restore the stepping dog to its normal position upon disengagement of said dog from the rack by the rocker, means to automatically restore the holding dog to its normal position, and. means on the dog rocker to arrest restoring movement of the holding dog and positioned in the line of thrust of the collisive means on the stepping dog against the collisive means on the holding dog.

2. A carriage feeding escapement mechanism,

as claimed in claim 1, having separate pivotal supporting means on the dog rocker aifording parallel pivotal axes for the respective dogs, and a single dog restoring spring connected with both dogs.

3. A carriage feeding escapement mechanism, as claimed in claim 2, having a single cushioned stop device for quietly arresting restoring movements of both dogs.

4. In a carriage feeding escapement mechanism, the combination of a dog rocker, spring restored stepping and holding dogs pivotally mounted on the dog rocker for collision of the stepping dog with the holding dog while the latter is in restored position to thereby limit stepping movement of the stepping dog from restored position, and means on the dog rocker to arrest restoring movement of said dogs at their respective restored positions, each of said dogs having a nose at one side of its pivot for toothed engagement of a carriage feed rack therewith, which dog noses are substantially in register while the stepping dog is in collisive engagement with the restored holding dog.

5. In a carriage feeding escapement mecha-' nism, the combination of a dog rocker, spring restored stepping and holding dogs pivotally mounted on the dog rocker for collision of the stepping dog with the holding dog While the latter is in its restored position to thereby limit stepping movement of the stepping dog from its restored position, means to arrest restoring movement of said dogs at their respective restored positions, each of said dogs having at one side of its pivot for toothed engagement of a carriage feed rack therewith a nose which substantially registers with the nose of the other dog when the stepping dog collides with the restored holding dog, said dogs each having a tail at the opposite side of its pivot, and a contractile restoring spring for both dogs extending between and connected to the tails of the dogs.

6. In a carriage feeding escapement mechanism, the combination of a dog rocker, a spring restored holding dog mounted on the dog rocker to shift from and to a restored position, a spring restored stepping dog mounted on the dog rocker to shift from and to a restored position, stop means to limit restoring movement of the stepping dog, stop means to limit restoring movement of the holding dog, said dogs each having a nose for toothed engagement of a carriage feed rack therewith, and said stepping dog and the stop means for the holding dog being engageable with said holding dog at opposed points to limit stepping movement of the stepping dog against its restoring spring force.

JOSEPH P. BARKDOLL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 923,106 Barney May 25, 1909 1,116,144 Smith Nov. 3, 1914 1,219,213 Anderson Mar. 13, 1917 1,394,614 Dudley Oct. 25, 1921 1,998,829 Avery Apr. 23, 1935 

